Background
Bob Weir told a nice story about the writing of this song in an interview with David Gans on "Dead To The World" on KPFA:

One of the reasons that Willie wanted to work with us is he wanted to sort of bust out of the blues bag. And he wanted to go into, you know, some more extended chord changes and stuff like that. And so we started working this thing up, and he liked it, and he started writing stuff. And by the time we had sort of fluffed up a verse and a chorus, musically, he handed me a sheet of paper. "Now, you go ahead and sing this." And I was reading it, and it was so simple, and I was thinking to myself, this is awful simple, this is really pretty simple-minded stuff. And it's really a great honor to be working with the legendary Willie Dixon and stuff like that, but you know, maybe he's gettin' old or something like that. Maybe he doesn't have the grip that he used to have, the edge that he used to have. And he was sitting back there, saying, "Go ahead and sing it now. You know, you play it and sing it, too." And so I figured, well, I gotta to that, you know. We're working with him. And so we started playin' it.
And I read the lyrics off the page, and when I was done, I was transported somewhere else. I was speechless at what had just happened. Just the elegance of the statement that had just come through my lips. And he'd been watching me. You know, he's an old guy, he's seen me go through all these changes, he'd been watching me. And so, I'm sitting there with my mouth open and my eyes just sort of *wide* open, and he's just crackin' up. "Now you see, now that's the wisdom of the blues."